Astronomy

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Messier 86, M87 (Markarian's Chain of Galaxies)

Taken with Orion ED80 at f/5.0 with Taurus Tracker III 0.65 reducer, canon 20d with noise reduction at 1600iso. This is a single 40min exposure at 1600 iso at about 60 degrees F in Kingman, AZ. This represents near the exposure limit of the camera. While it can do 60mins, there is a lot of noise that is difficult to process out with darks and in-camera noise reduction. 20min seems to be optimal for this camera.

Messier 86

Lenticular (S0) Galaxy M86 (NGC 4406), type S0, in Virgo

Right Ascension 12 : 26.2 (h:m)
Declination +12 : 57 (deg:m)
Distance 60000 (kly)
Visual Brightness 8.9 (mag)
Apparent Dimension 7.5x5.5 (arc min)


Discovered 1781 by Charles Messier.


Excerpt from seds.org:

Messier 86 (M86, NGC 4406) is one ogf the brightest member galaxies of the Virgo Cluster og Galaxies, and situated close to that cluster's apparent center.

M86 has been discovered and cataloged by Charles Messier on March 18, 1781 when he also cataloged 7 more nebulous objects in the same region of the sky, all member galaxies of the Virgo Cluster, and in addition, globular cluster M92.

This bright giant galaxy is either an elliptical of type E3 or a lenticular galaxy of type S0_1(3); modern classifications apparently tend more to the lenticular classification, NED gives both classes. It has a conspicuous system of faint globular clusters, suggestions of which can be just seen in the DSSM image of this galaxy. However, this system of globulars is far less populated than that of its giant neighbor to the SE, M87. To the lower left is a very small and faint dwarf elliptical companion. Several condensations may be found around this galaxy in our image, especially to the lower part, and the DSSM photo (here to the upper edge), they may be globular clusters belonging to this galaxy.

M86 lies well in the heart of the Virgo Cluster of galaxies and forms a most conspicuous group with another giant, M84. Below M86 in our image is NGC 4402, a dim (11.5 mag) edge-on spiral. This group may be viewed in one field even at medium power, so that it is often photographed and we have more images including M84 and M86. Deep images of this group have revealed that these galaxies are actually much larger than indicated in conventional images, as the one in this page. In addition, we have images of the whole central part of the Virgo Cluster: M87 together with Markarian's chain around M84 and M86.

M86 is the galaxy which has the fastest approaching velocity, and thus the highest blue shift, of all Messier galaxies (and thus all Messier objects): It is approaching us at 419 km/sec ! (Sky Catalogur 2000.0; NED has a slightly lower value of 281 km/sec which makes it second to M90.) Holmberg (1964) has therefore speculated that it should be a close foreground galaxy and not a Virgo cluster member. This speculation has been referred to, and occasionally been adopted, by several sources, including George R. Kepple's and Glen W. Sanner's Observer's Guide. However, the present authors join the view of most modern sources, including the Sky Catalogue 2000.0, R. Brent Tully's Nearby Galaxies Catalog, Becvar's earlier Atlas Coeli, and (implicitely) the Webb Society's Deep Sky Observer Handbook (which has it in the Virgo Cluster description), and thinks it is just this high approach velocity which indicates that M86 is most probably a true cluster member, because of the following reason: In this case, the high velocity value would indicate that M86 is moving at a peculiar velocity of more than 1500 km/sec, which points by chance in a direction toward us. But this is not totally uncommon in huge clusters of galaxies as the Virgo cluster, because due to its enormous mass, this huge agglomeration of mass has a strong gravitational field. This strong gravitational field could easily accelerate a galaxy to the high velocity observed for M86; it would be much more difficult to find an explanation for such a high velocity for a field galaxy !

The Virgo cluster membership of M86 is also suggested by its more or less obvious interaction with the intergalactic gaseous matter in the Virgo cluster, which was reported from X-ray observations, discovered by Forman et.al. (1979); for a recent review see e.g. Rangarajan et.al. (1995). Moreover, M86 does not hold the record: Another Virgo cluster member, IC 3258, approaches us at 517 km/sec. Our Galaxies in the Virgo Cluster page lists more fastly approaching (and receding) Virgo Cluster members.

The X-ray gas tail of M86 is dramatically apparent in recent Chandra X-ray Observatory images of this galaxy.

Additional evidence for M86's Virgo Cluster membership may be derived from deep images of this galaxy which show slight disturbations of its faint outskirts, probably caused by gravitational interaction with its neighbors.

On deep images like this one, the outskirts of M84 and M86 seem to overlap; the angular distance between their centers of about 16.5 arc min corresponds to a projected distance of only roughly 300,000 light years. This, however, is probably a perspectivic effect, as otherwise their outlayers would be even much more distorted; there is probably some radial distance, or distance difference from us, between these two galaxies; it is not known which one is a bit closer to, and which a bit farther away from us.

On M86's fast motion through the intergalactic medium of the Virgo Cluster (the "Intra-Cluster Matter", ICM), the galaxy's interstellar matter collides at high velocity with this material, and is probably "ram-pressure stripped" from the galaxy (Rangarajan et.al. 1995). On this occasion, the matter is heated. Dust within this matter, previously held within colder gas clouds, is probably destroyed when the matter heats during the collision. Analysis of the ram pressure indicates that, in addition to its peculiar radial velocity with respect to the Virgo Cluster, M86 may have a tangential velocity component of about 500 km/sec in southward direction.

M86, together with M84, can be found rather easily, by pointing your telescope almost exactly half-way between Denebola (Beta Leonis) and Vindemiatrix (Epsilon Virginis). Both galaxies will show up in the same low (or medium) power eyepiece, and can serve as starting point for Observing the Virgo Cluster. Alternatively, you can find M84 and M86 from the "Big T" asterism including 6 Comae Berenices which is near M98, M99, and M100 at 1 deg south and 1.5 deg East of this asterism's "Southern Tip" star. Or both these galaxies are easily found from M87 which is about 1 degree southeast.


The Virgo Cluster of Galaxies
Also: Coma-Virgo cluster of Galaxies
This giant agglomeration of galaxies is the nearest big cluster of galaxies, the largest proven structure in our intergalactic neighborhood, and the most remote cosmic objects with a physical connection to our own small group of galaxies, the Local Group, including our Milky Way galaxy. This structure is another discovery by Charles Messier, who noted behind his entry for M91 (here quoted from Kenneth Glyn Jones' book):

``The constellation Virgo and especially the northern wing is one of the constellations which encloses the most nebulae. This catalog contains 13 which have been determined, viz. Nos. 49, 58, 59, 60, 61, 84, 85, 86, 87, 88, 89, 90 and 91. All these nebulae appear to be without stars and can be seen only in a good sky and near meridian passage. Most of these nebulae have been pointed out to me by M. Méchain.''
Together with his later entries, 98, 99, and 100, Messier had cataloged 16 members of the Virgo cluster which he viewed as a 'cluster of nebulae'. Pierre Méchain, in a letter of 1783, stated that he had seen even more "Nebulae" in this region which "Messier had not seen;" unfortunately, no records are known indicating which galaxies this may have been.
Our image shows a star chart drawn by Messier, cropped from a larger chart he published with his observations of the comet of 1779 (all 16 Messier objects are marked in this drawing). This discovery occured in 1781, significantly more than a century before the true nature of galaxies was realized in the 1920s ! A long history of exploration still had to pass until its nature as a physical cluster of galaxies became obvious.

Messier galaxies which are Virgo cluster members: M49, M58, M59, M60, M61, M84, M85, M86, M87, M88, M89, M90, M91, M98, M99, and M100.


The Virgo Cluster with its some 2000 member galaxies dominates our intergalactic neighborhood, as it represents the physical center of our Local Supercluster (also called Virgo or Coma-Virgo Supercluster), and influences all the galaxies and galaxy groups by the gravitational attraction of its enormous mass. It has slowed down the escape velocities (due to cosmic expansion, the `Hubble effect') of all the galaxies and galaxy groups around it, thus causing an effective matter flow towards itself (the so-called Virgo-centric flow). Eventually many of these galaxies have fallen, or will fall in the future, into this giant cluster which will increase in size due to this effect. Our Local Group has experienced a speed-up of 100..400 km/sec towards the Virgo cluster. Current data on the mass and velocity of the Virgo cluster indicate that the Local Group is probably not off far enough to escape, so that its recession from Virgo will probably be halted at one time, and then it will fall and merge into, or be eaten by the cluster, see our Virgo Cluster & Local Group page.

Because of the Virgo Cluster's enormous mass, its strong gravity accelerates the member galaxies to considerably high peculiar velocities, up to over 1500 km/sec, with respect to the cluster's center of mass. Investigations over the past decades have revealed a quite complex dynamic structure of this huge irregular aggregate of galaxies. The Virgo cluster is close enough that some of its galaxies, which happen to move fast through the cluster in our direction, exhibit the highest blue-shifts (instead of cosmological redshifts) measured for any galaxies, i.e. are moving toward us: The record stands for IC 3258, which is approaching us at 517 km/sec. As the cluster is receding from us at about 1,100 km/sec, this galaxy must move with over 1,600 km/sec through the Virgo Cluster's central region. Analogously, those galaxies which happen to move fastest away from us through the cluster, are receding at more than double redshift than the cluster's center of mass: The record is hold by NGC 4388 at 2535 km/sec, so that this galaxy moves peculiarly in the direction away from us at over 1,400 km/sec.

Our image shows the central portion of the Virgo Cluster of Galaxies, and is centered on the giant elliptical galaxy M87 which is considered to be the dominant galaxy of the whole giant cluster, situated close to its physical center. The two bright galaxies on the right (west) are (right-to-left) M84 and M86; starting from these two, a chain of galaxies ("Markarian's chain") stretches well to the upper (northern) middle of our image (and beyond, well to M88 which is slightly outside above the sky area photographed our image). The appealing group around these two giant lenticulars is described with M84, and in our collection of images with M84 and M86; we also have images of M87 together with Markarian's chain around M84 and M86. To the left (east) of M87, the considerably bright elliptical (type E0) M89 occurs (on roughly the same declination as M87), above it and slightly more left is the inclined and conspicuous spiral M90, while below (south) and left of M89 there is M58, sitting just on the edge of our image.